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Four different fish species (Bluegill Sunfish, Rainbow Trout, Fathead Minnow and Oryzias latipes) were exposed to 44PD in a static test (Oryzias latipes were exposed in a semi static test). All tests were carried out according to (then existing) guidelines and under GLP. The 96hr-LC50 values for the different species were close to each other, the lowest 96hr LC50 value was obtained for Fathead Minnow and was 0.13 mg/L. The highest 96hr LC50 value was obtained for Rainbow trout and was 1.4 mg/L.

For long-term toxicity of 44PD to fish, test results from 6PPD were used. Based on structural analogy it is considered that these results can also be used for 44PD. The chronic toxicity in fish of N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD) was assessed with Oryzias latipes in a Early-Life Stage Toxicity Test according to OECD Guideline 210. The 30d NOEC is 0.0037 mg 6PPD/L. This corresponds to a 30d NOEC of 0.0030 mg 44PD/L.

For aquatic invertebrates, two independent short term studies were performed to test the toxicity of 44 PD (CAS 101-96-2) to Daphnia magna. Both studies were carried out according to (then existing) guidelines and under GLP. The results from both studies are quite similar: 48 hr LC50 values of 0.540 and 1.4 mg/L were obtained.

For long term toxicity to Daphnia, test results from hydroquinone, one of the main hydrolysis products of 44PD, were used. Toxicity was investigated in a study conducted according to OECD Guideline 211 (Daphnia magna Reproduction Test) under GLP. Effect parameters observed were inhibition of reproduction, cumulative number of surviving offspring, first day of birth, death and body length of parent Daphnias, occurrence of aborted eggs and male individuals. A 21 d NOEC=0.0057 mg HQ/L based on recalculated measured initial concentration was found. This corresponds to a 21d NOEC of 0.0114 mg 44PD/L after correction for molecular weight.

An algal growth rate inhibition test on 44PD was carried out according to Japanese guidelines and under GLP. The result of the test was a 72 hr EC50 for algal growth rate inhibition of 0.939 mg/L. The 72 hr NOEC that was derived from this test was 0.0958 mg/L.

A study on the toxicity of Vulkanox 4005 to bacteria was carried out in accordance with Council Regulation (EC) No 440/2008, Method C.11 ”Biodegradation: Activated Sludge Respiration Inhibition Test” (2008). This test method is equal to OECD Guideline 209 (1984). Vulkanox 4005 showed 100.00 % respiration inhibition of activated sludge at the highest test item concentration of 524.3 mg/L. The EC50 is 90.78 mg/L.

For the PNEC calculation, the value of 0.003 mg 44PD/L was used as starting point. This value was obtained through read-across from a long-term toxicity to fish study on 6PPD.